Bring pot of salted water to boil. Add peas and cook 2 to 3 minutes, or until peas float to top and are crisp-tender. Using slotted spoon, lift into bowl of ice water to shock (quickly stop cooking). Reserve cooking water in pot (for cilantro oil).

Bring pea-cooking water to simmer. Add cilantro and cook 10 seconds. Remove from pot with slotted spoon and immerse in ice water to shock. Drain cilantro, squeeze out excess water and pat dry. Add to blender with oil and purée until smooth. Season with salt and pepper to taste.

Place sheet of plastic (freezer bags work best) or waxed paper over base of tortilla press. Place one dough ball on plastic and gently press down with hands until dough is about 3⁄4″ thick. Top with another sheet of plastic. Close press and push to flatten into a tortilla. Open press and peel tortilla from plastic. Place tortilla on kitchen towel and cover with another towel. Repeat with remaining dough.

Heat nonstick pan (cast iron is best) over high heat. When pan is very hot, pour 1 tsp oil into pan and swirl to coat. Add 1 or 2 tortillas to pan. Cook 15 to 30 seconds per side, or until they appear dry. Move tortillas to kitchen towel and let rest, uncovered.

Heat 1″ vegetable oil in deep pot over high heat until oil reaches 340° to 350°F. Add 1 or 2 tortillas to oil. Cook 30 seconds per side, or until very crispy. Tortillas will puff up and sizzle as they release moisture. Transfer fried tortillas to paper towel-lined rack and repeat with remaining tortillas. Reserve tostadas.

Grill Fish

Heat grill to medium-high, about 400°F. Brush fish, including skin-side, with 1 tbsp vegetable oil. Season with salt and pepper. Place on grill and cook with lid closed 6 to 8 minutes, or until fish is cooked through. Remove from grill and let rest 5 minutes. Slice or flake into 8 portions.

Prep And Assemble Tacos

Season radishes with salt and let sit 10 minutes.

Spread pea purée over each tostada. Place fish over pea purée and scatter with salted radishes and crumbled Chicharrón (if desired). Drizzle with cilantro oil and spritz with lime juice.